Carcass traits and M. longissimus lumborum palatability attributes of calf- and yearling-finished steers

¹ Department of Animal Science, University of Nebraska, Lincoln, NE 68583-0908

^* To whom correspondence should be addressed. E-mail: ccalkins1{at}unl.edu.

	Abstract

A two-year experiment was conducted to compare carcass characteristics and meat palatability attributes of steers (3/4 British, 1/4 Continental) finished post-weaning as calves or yearlings. Calves and yearlings of the same contemporary group were designated to a finishing system at weaning. Calves (n=73) were finished in the feedlot (191 d) on a high concentrate diet. Yearlings (n=84) grazed crop residues after weaning followed by spring and summer pasture grazing and concluded with a short finishing period (91 d) in the feedlot. All steers were fed to a constant fat thickness endpoint of 1 cm. M. longissimus lumborum steaks from each production system were aged for 7, 14, or 21 d for Warner-Bratzler shear force determination and 7 or 14 d for in-house sensory panel evaluation. Insoluble, percent soluble and total collagen were determined. Yearlings produced heavier (P < 0.001) carcasses with larger (P < 0.001) longissimus muscle areas and lower (P < 0.001) marbling scores and quality grades. Calves possessed higher amounts of total collagen (P < 0.001) than yearlings with a significantly higher percentage of soluble collagen when compared to yearlings (39.72 vs 24.38%). Calves produced steaks with lower (P < 0.001) shear force values and higher (P < 0.001) sensory ratings for flavor. The USDA Choice steaks from calves were more (P < 0.001) tender and more (P < 0.050) palatable than Choice steaks from yearlings, and USDA Select steaks from calves were rated more tender (P < 0.001), juicy (P = 0.012), and desirable (P < 0.001) than Select steaks from yearlings. As expected, increasing aging time from 7 d to 14 d to 21 d produced steaks with lower (P < 0.001) shear force values, regardless of production system. Risk probabilities showed 1.24% of steaks from calf-finished steers and 21.22% of steaks from yearling-finished steers to be "tough". Sensory rating probabilities showed steaks from calves most likely to be "desirable" for tenderness, while steaks from yearlings were most likely to be "undesirable" for tenderness, juiciness, flavor, and overall acceptability. Thus, calf-finished steers produce carcasses superior in quality and palatability when compared to steaks from yearling-finished steers. However, yearling-finished steers can produce tender beef with extended aging.

Key Words: Beef, Production Systems, Meat Quality, Collagen

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